Humic acids characterization by EDXS and ¹³C NMR spectroscopy

Abstract

Determination of humic acids spectral characteristics performed fast and convenient method for their quality evaluation. Humic acids (HA) were isolated from five different soil types (Luvi-haplic Chernozem, Haplic Luvisol, Haplic Cambisol, Leptic Cambisol and Eutric Cambisol) and from compost. Basic soil characteristics were determined by commonly used methods. Fractional compositon of humus showed that humic acids content was decreasing in order: compost > Luvi-haplic Chernozem > Haplic Luvisol > Eutric Cambisol > Haplic Cambisol > Leptic Cambisol. Isolated humic acids preparations were characterized comparatively by chemical and spectroscopic methods. Elemental analysis showed the highest carbon content in Luvi-haplic Chernozem HA. The lowest carbon amount was in Eutric Cambisol. Energy–dispersive X-ray spectroscopy detected elementsin situin HA molecule. All samples contained Fe, Cu, Zn, Ti, Ca, K, S, P, Si and Br. Practically no differences in elements content between soil humic substances and compost were detected. The amount of aromatic carbon was higher in Luvi-haplic Chernozem to compare with other samples. Humic acids isolated from Cambisols, on the basis13C NMR spectroscopic data, showed that all samples contained less aromatic carbon and significantly more aliphatic carbon.

Humic and Fulvic Acids as Potentially Toxic Metal Reducing Agents in Water

“…Following a simple extraction procedure humic and fulvic acids were separated (0.29 and 0.15 g/100 g lignite, respectively). The determined content of lignite in humic and fulvic acids appeared to be within the limits previously reported in the literature . It is known that lignite contains by nature heavy metals .…”

Humic and Fulvic Acids as Specific Sorbents of Herbicides in Water

“…The lignite's content in HAs and FAs was found in line with that reported in literature. [ 26,27 ] In addition, the water and ash content of lignite was found to be similar to other Greek lignites. [ 28 ]…”

Chemical, Spectral and Morphological Characterization of Humic Acids Extracted and Membrane Purified from Lignite

“…UV-Visible (UV-Vis) spectroscopy can provide useful information about the composition and origin of HAs. The (E 4 /E 6 ) ratio and the ΔlogK coefficient have proven to be useful to evaluate the degree of humification of HAs extracted from different sources [17][18][19]. Fourier transform infrared (FT-IR) spectroscopy provides useful insight into the nature, reactivity and structural arrangement of oxygen-containing functional groups in HAs [20].…”